1. Field
This invention pertains to musical instruments. It is directed to end-blown wind instruments played in the manner of the Didgeridoo (Yidaki) of Aboriginal players of Australia's Northeast Arnhem Land. It provides an end-blown instrument that emulates the sound of the Didgeridoo while being designed around one or more venturi chambers. Unlike other didgeridoos, it consists of a venturi chamber(s) tapered from the proximal to the distal end—or may be modified by creating two venturi chambers with cylinders of diminishing diameter toward the distal end. The mouthpiece is at the largest (proximal) end—i.e. the reverse of the yidaki or Didgeridoo design.
2. Background
The shapes of tubular end-blown wind instruments played by mouth are dominantly of three types: straight cylinders, tapered cones, and combinations of straight cylinders and cones—none of which decrease in diameter from the proximal end. Any of these types may also include a flair at the distal end. No end-blown wind instrument before this invention (the “Venturi-Didgeridoo”) is constructed in such a way that the ratio of the diameter of the proximal end to that of the distal end creates a venturi effect.
The Australian Yidaki or Didgeridoo differs from all other end-blown instruments in that it does not have a small-diameter mouthpiece (e.g., trumpets, trombones, French Horns, etc.) The mouthpiece of a trombone narrows to a diameter of c. 9.3 mm. Even the tuba constrains air to an outlet of about 10.89 mm, whereas the didgeridoo has an opening that varies from about 28 mm to 40 mm or more. The result of this is that in playing the didgeridoo the lips do not vibrate with the high frequency of its distant cousins in the brass instrument family—but with loosely vibrating or “fluttering” lips, somewhat like the vibration rate of a Bronx Cheer or, technically, an “unvoiced linguolabial trill”. This produces the low, haunting, idiosyncratic sound of the didgeridoo.
Traditional didgeridoos are made from the trunks (sometimes branches) of live Eucalyptus trees that have been hollowed out by termites. After tapping on various such trees, one is chosen by the artisan and cut down. The termites are driven out by the application of hot coals, after which the interior of the trunk is scraped and further hollowed out. The narrowest end is chosen as the point at which to form the mouthpiece. Sometimes the diameter is small enough (c. 28 mm-40 mm) to accommodate the loose, fluttering-lip technique used to play the instrument. However, the proximal diameter of a Eucalyptus didgeridoo is usually larger than 35 mm, so a beeswax mouthpiece may be shaped to reduce the diameter to a comfortable playing size. The preferred pitches of Aboriginal players are two octaves below Middle C and range in pitch from B-2 to E-2 (61.7 hz to 82.4 hz) with a decided preference for C#-2 (69.3 hz)
The wavelength of a sound produced in an open cylinder or pipe is very close to twice the length of the pipe itself. A 48″ un-tapered cylinder will play a fundamental note of C#. Most Australian didgeridoos are 48″ or longer in length. However, if a didgeridoo is not a pure cylinder but becomes a tube with flair toward the distal end, the fundamental pitch will rise. This rise in pitch is found in all such didgeridoos. However, because of the complex inner shape of an instrument bored out by termites beginning at the base of the trunk, it is impossible to predict the resultant pitch with any precision. An examination of 16 top-concert-grade didgeridoos with pitches of C# at an Australian website (didjshop.com) shows an average length of 53.09″. A 53″ didgeridoo made of Bloodroot Eucalyptus (one of the two or three best woods for didgeridoos) weighs about 8.5 lbs.
Because of the weight and length of traditional didgeridoos, alternative materials and designs have been sought to create didgeridoos that are lighter, shorter, more durable, and portable.
All prior attempts to make a portable didgeridoo have dealt with the problem of pitch being related to length either by cutting the instrument in pieces that can then be fitted together—or by creating a serpentine airway within a box (U.S. Pat. No. 6,664,454). In this case, the lowest pitch of the “Didjbox” remains directly related to the length of the air column—which perforce must equal that of a standard, straight cylinder. Coiling, twisting, or convoluting the air column of a wind instrument does not in itself change its pitch (e.g. French Horn vs Herald Trumpet). Changing the air column length, however, does. The original Didjbox (U.S. Pat. No. 6,664,454) has a length of 24″, a 2″ mouth, a 3″ distal bell, and weighs 1.75 pounds. Its internal air column is slightly over 48″ (to result in a pitch of C-2). While portable, it is still rather large. Subsequent Didjbox iterations have achieved reduced overall size and weight by considerably reducing the diameter of the air column. While the resulting designs are lighter and smaller, the reduced internal diameters inevitably have a dampening impact on the sound characteristics generated.
Another prior attempt to increase didgeridoo portability is the Didgeridoo Store's “Travel Didgeridoo”: www.didgeridoostore.com/didgeridoo_modern3.htm. Its sections can be linked to create a 66″ instrument with a 4.5″ bell. For travel, two 18″ sections can be nested within the largest section. The third section is placed in the travel bag next to the collapsed sections—making total dimensions of 18″×6.5″. Portable, but still large.